Rigid polyurethane foam is processed using a cast process or spray process. The cast process is generally utilized for block foam production, continuous double band lamination (DBL), and discontinuous panel production (DCP).
Block foam is produced by known discontinuous production or continuous rigid slab-stock production methods. If necessary for specialty products, the block foam is cut after production to the required shape, and is typically glued to facings to make the finished specially product. Such products find use in the building industry, in truck insulation, and in the form of half shells for pipe insulation.
Double band lamination is a continuous panel production process with both sides laminated with all kind of flexible or rigid facing materials. The polyurethane foam core is sandwiched between those facings and applied as insulation for floors, walls and roofs. Sandwich panels with a rigid metal facing are structural building elements and can be applied as roof and wall construction elements such as cold-store panels, garage doors, refrigerated trucks, and for similar uses. Sandwich panels with non-metal rigid facing, e.g., gypsum board or wood, are used in the manufacture of prefabricated houses or other building structures.
Anyone unfamiliar with the art of forming polyurethanes, polyisocyanurates, or related polymers desiring any further details already known by those of ordinary skill in the art of producing polyurethane foams, polyisocyanurate foams, or polyurethane-modified polyisocyanurate foams may refer for example to U.S. Pat. Nos. 3,954,684; 4,209,609; 5,356,943; 5,563,180; and 6,121,338, and the references cited therein.
There has been a transition in the type of blowing agents over the last decade from CFC's to HCFC's in accordance with the Montreal Protocol because of the ozone depletion potential (ODP) of CFC's. For countries in which the use of CFC's was abolished, this conversion typically involved switching from CFC-11 to HCFC 141b. However, the industry must soon convert from HCFC's to a third generation blowing agent with non-ODP and low global-warming potential (GWP). Alternative blowing agents are HFC's and hydrocarbons.
In practice, systemhouses prepare ready-to-use blends of all ingredients but the isocyanate(s). Typical ingredients involved are polyols, chain extenders and/or crosslinkers, water as auxiliary blowing agent, flame-retardants, catalysts and surfactants.
Fire resistance is an important property of construction materials. Bromine, chlorine and phosphorus compounds or mixtures thereof have been used effectively to comply with applicable fire safety standards. However, in addition to high effectiveness as flame retardants, it is desired to provide liquid flame retardant compositions having low viscosity that can be easily incorporated in the various types of processes used in manufacturing of rigid polyurethane foams. In addition, such compositions need to have good shelf stability, and in order to be accepted in the marketplace such compositions need to be highly cost-effective to the user.
One objective of this invention is thus to provide effective, liquid flame retardant compositions with relative low viscosity that have good shelf stability and that can be easily blended with the other ingredients to obtain a system useful for producing flame retardant rigid polyurethane foam. Another objective is to provide a flame retardant composition which is particularly useful for double band lamination that provides good hardness development.